Laparoscopy is one example of microinvasive medial methods. An artificial port to the abdominal cavity of a patient through the abdominal wall of the patient is formed by means of a trocar. An endoscope and/or further medical instruments (for instance forceps, scissors, acutenaculums) can be introduced into the abdominal cavity through the lumen of a trocar's cannula remaining in the abdominal wall during the laparoscopic intervention. During laparoscopy, the abdominal cavity is filled with carbon dioxide or another gas in order to form a pneumoperitoneum, a cavity facilitating the medical intervention. Without specific measures, the gas would leak through the lumen of the trocar's cannula. Therefore, numerous approaches have been developed for sealing the lumen of the trocar's cannula as tight as possible, both in an empty state and when an instrument is introduced. Partly similar problems can arise at a working channel of an endoscope or when a catheter is introduced into a blood vessel. In the latter case, however, leakage of blood rather than gas needs to be prevented.
In U.S. Pat. No. 4,857,062, a valve for the introduction of a catheter to an artery is described. For sealing purposes, a duck bill shaped first element and a second flexible element are provided, wherein the second flexible element is compressed in order to form a fluid tight sealing with a catheter. Both elements are arranged fixedly an in series in a housing.
In WO 93/01850 A1, a lever actuated sealing for a trocar is described. An elastomeric septum with an orifice is stretched by means of several levers, whereby the orifice is expanded.
In U.S. Pat. No. 5,366,446, an introducer assembly for use on the skin of a patient is described, the introducer assembly being provided for the introduction of tubes with different outer diameters. The assembly comprises a membrane of a pierceable elastomeric material in the center of a bellows.
In EP 0 630 660 A1, a sealing assembly for accommodating of a surgical instrument is described. The sealing assembly comprises a duck bill seal or an arrangement of a plurality of seal members, a part of which is slotted in star-shape and which partially overlap each other and a part of which is shaped conically.
In EP 0 746 359 B1, a catheter check valve is described. For sealing purposes, a rubber seal with an orifice and a duck bill valve with a straight slit distal of the rubber sealing are provided.
In WO 2010/045702 A1, a disposable sealing for a trocar is described. The disposable sealing is approximately cup-shaped with cuts crossing each other at the bottom.
In U.S. Pat. No. 4,430,081, a cannula for use with angiography catheters is described. A first sealing with a slit, a second sealing with a hole and a third sealing with a flapper are provided adjacent to each other for sealing against ingression of air or leakage of blood from a blood vessel.
In WO 91/12838 A1, an infusion port with several elastic discs in series is provided, each of the discs comprising a circular orifice or star-shaped slits, one disc rotated with respect to the other.
In EP 0 536 459 A1, a trocar sleeve for the introduction of a medical instrument is described. A sealing assembly for sealing an axial passage and for sealing a hollow shaft both when an instrument is introduced and when no instrument is introduced comprises one or more septums of elastic material with cross-shaped slits staggered with respect to each other.
In WO 94/01149 A1 and DE 693 29 286 T2, a valve for an introduction assembly is described. A body of silicone or of another elastomeric material comprises a cylindrical wall inclosing a bore. One end of the cylindrical wall and of the bore is closed by a wall with a central orifice. The other end of the wall and of the bore is closed by two inclined plates with a slit there between.
In WO 98/32484 A1, an instrument for introducing catheters with a hemostatic valve is described. A sealing element comprises two perforated supporting discs, wherein a sealing disc of soft elastic foam plastic with radial slits is provided between the supporting discs.
In EP 1 269 925 A1, an access cannula for endoscopic surgery is described. A double disc valve comprises two discs with three-beam star-shaped slits each, wherein the slits of both discs are arranged staggered with respect to each other.
In EP 1 350 476 A1, a trocar sleeve with a valve is described. The valve comprises an introduction region with wall sections which converge towards one another in the distal direction and which are provided as sloping surfaces, and sealing lips abutting one another elastically.
In DE 297 01 600 U1 the valve mechanism for medical applications is described. Two similar valve discs with a centrally located slit each are arranged in a casing and form an angle in the range of 60 degree to 90 degree.
In DE 601 05 973 T2 a hemostasis valve is described comprising proximal valve sealing with a slit and a distal valve sealing with a slit. A positioning protrusion restricts the relative rotation of the valve sealings.
In US 2006/0135977 A1 a trocar sealing structure with two conical sealing sections is described.
Each of the sealing means described provides specific advantages and disadvantages. For many applications, no satisfactory solutions have been found or, at least, further improvements are desired. This holds particularly with regard to the fact that sealing means shall fulfill numerous requirements simultaneously. In particular, sealing means are required to be fluid tight, robust, reusable and for this purpose in particular autoclavable, to resist axial motion of a medical instrument as little as possible, to facilitate lever type manipulation, or tilting, of a medical instrument introduced into the sealing means and at the same time to stay fluid tight, and to allow cost effective production. Furthermore, sealing means are required to be cleanable with little effort, to provide a compact construction, in particular a short installation length (metered from the proximal to the distal end of the sealing means), and to be suitable for medical instruments with different cross sections. Furthermore, it is required that medical instruments with cross sections varying in longitudinal direction, in particular with undercuts, steps, offsets, and soft tissue can pass the sealing means in the direction from distal to proximal as well, thereby not getting stuck or caught in another way by the sealing means.